1. Field of Invention
The present invention relates to semiconductor-on-insulator devices and methods of making, and in particular to structures and/or methods of cooling such devices.
2. Description of the Related Art
Semiconductor devices, such as devices including transistors, for example, produce heat. As device density increases, the problem of removing the heat created by operation of the devices intensifies.
A semiconductor-on-insulator (SOI) device includes a thermoelectric cooler on a back side of the device. The thermoelectric cooler is formed on a thinned portion of a deep bulk semiconductor layer of the SOI device. The thermoelectric device includes a plurality of pairs of opposite conductivity semiconductor material blocks formed on a metal layer deposited on the thinned portion. The thinning of the thinned portion may be accomplished in multiple etching steps of the deep silicon layer, such as a fast etching down to an etch stop and a slower, more controlled etch to the desired thickness for the thinned portion.
According to an aspect of the invention, a semiconductor device includes a surface semiconductor layer; a buried insulator layer below the surface semiconductor layer and in contact with the surface semiconductor layer; a deep semiconductor layer having a upper surface in contact with the buried insulator layer, the deep semiconductor layer having a thinned portion, the thinned portion having a back surface which is opposite the upper surface; and a thermoelectric cooler on the back surface of the thinned portion.
According to another aspect of the invention, a semiconductor device includes a surface semiconductor layer; a buried insulator layer below the surface semiconductor layer and in contact with the surface semiconductor layer; a deep semiconductor layer having a upper surface in contact with the buried insulator layer, the deep semiconductor layer having a thinned portion, the thinned portion having a back surface which is opposite the upper surface; and cooling means on the back surface of the thinned portion.
According to yet another aspect of the invention, a method of making a semiconductor device includes the steps of: providing a semiconductor-on-insulator (SOI) wafer having a surface semiconductor layer and a bulk semiconductor layer with a buried insulator layer therebetween; thinning at least a portion of the bulk semiconductor layer of the SOI wafer, thereby producing a thinned portion of the bulk semiconductor layer; and forming a thermoelectric cooler on a back side of the thinned portion of the bulk semiconductor layer.